96 resultados para Enzymes activity


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P. brasiliensis parasitizes various human tissues and proteinases exported by this fungus may allow it to metabolize and invade host tissues. The influence of the culture medium on the production of proteinases by P. brasiliensis isolates was studied and the export of these enzymes was followed as a function of culture time. The fungus was grown in neopeptone, BSA, elastin or collagen medium. The culture medium was assayed for azocollytic, elastinolytic and caseinolytic activity. Proteolytic activity was also analysed by electrophoresis of the culture medium on gelatin and casein substrate gels. P. brasiliensis expressed relatively high levels of azocoll, elastin and casein degrading activity in all types of medium, except in neopeptone medium. Generally, expression of azocollytic activity peaked during the third week of culture and caseinolytic activity during the fourth week of culture. Azocollytic activity was highest at pH 4.0 and caseinolytic activity at pH 8.0. Elastinolytic activity was also highest at pH 8.0. This activity, as well as the others, may provide the fungus with a source of carbon and nitrogen and may also be responsible for the invasion of host tissues, such as pulmonary elastic fiber, by P. brasiliensis.

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Pectinases are a big group of enzymes that break down pectic polysaccharides of plant tissues into simpler molecules like galacturonic acids. It has long been used to increase yields and clarity of fruit juices. Since pectic substances are a very complex macromolecule group, various pectinolytic enzymes are required to degrade it completely. These enzymes present differences in their cleavage mode and specificity being basically classified into two main groups that act on pectin smooth regions or on pectin hairy regions. Pectinases are one of the most widely distributed enzymes in bacteria, fungi and plants. This review describes the pectinolytic enzymes and their substrates, the microbial pectinase production and characterization, and the industrial application of these enzymes. © Pedrolli et al.; Licensee Bentham Open.

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The development of the germination process and drought stress during the drying of coffee can generate reactive oxygen species, which can be neutralized by way of antioxidant mechanisms. No studies related to antioxidant enzymes during the drying of coffee were found in the literature, and considering their importance, the enzymatic activities of superoxide dismutase (SOD), guaiacol peroxidase (GPOX) and glutathione reductase (GR), and also the hydrogen peroxide content were evaluated during the drying of two types of coffee bean, one processed as natural coffee and the other as pulped natural coffee. The results showed a reduction in the SOD, GPOX and GR enzymatic activities of the natural coffee as compared to the pulped natural coffee during the drying period. Moreover, the hydrogen peroxide content of the natural coffee was greater than that of the pulped natural coffee. These results suggest the development of oxidative stress during the coffee drying process, controlled more efficiently in pulped natural coffee by the early action of GPOX during the drying process. Nevertheless, differential responses by SOD isoenzymes and possibly the role of other peroxidases also appear to be involved in the responses observed. © 2013 Springer-Verlag Berlin Heidelberg.

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Tartrate-resistant acid (ACP) and alkaline phosphatase (ALP) activities were evaluated in the serum and bone of broiler chicks fed with various amounts of non-phytate phosphorus (NPP) or phytase. Data were analysed using a 4×3 factorial design containing four NPP levels per period. Analyses were performed in chicks aged 1-21 days (0.21; 0.29; 0.37; 0.45 ppm) and 36-42 days (0.13; 0.21; 0.29; 0.37 ppm) and under three different phytase level treatments (0, 500 and 1000 FTU/kg) for each period. In 42-day-old animals, the serum ACP and ALP activities did not differ in response to NPP and phytase levels and bone ACP activity decreased with increased phosphorus levels. We observed effects on ALP activity by approximately 70% in lower phosphorus (0.13 and 0.21) levels without phytase. The phytase addition decreased (P<0.05) ALP values in lower phosphorus levels. The bone ALP and ACP levels of 21-day-old animals were not affected by phosphorus or phytase. Pi depletion induces a significant increase in alkaline phosphatase synthesis, suggesting that the function of this enzyme is downregulated by phosphorus. © 2013 Copyright Taylor and Francis Group, LLC.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Sickle cell anemia (SCA) shows a pathophysiology that involves multiple changes in sickle cell erythrocytes, vaso-occlusive episodes, hemolysis, activation of inflammatory mediators, endothelial cell dysfunction, and oxidative stress. These events complicate treatment and culminate in the development of manifestations such as anemia, pain crises and multiorgan dysfunction. The aim of this study was to evaluate, in SCA patients, oxidative stress and antioxidant capacity markers, correlating them to treatment with hydroxyurea (HU), β-globin haplotypes and glutathione S-transferase polymorphisms (GSTT1, GSTM1 and GSTP1), in comparison to a control group (CG). The study groups were composed of 48 individuals without hemoglobinopathies (CG), SCA patients treated with HU [AF (+HU), N = 13] and untreated SCA patients [AF (-HU), N = 15], after informed consent. The groups were analyzed using cytological, electrophoretic, chromatographic and molecular methods and information from medical records. The GSTM1 and GSTT1 polymorphisms were determined by multiplex PCR, while the GSTP1 polymorphism by PCR-RFLP. Biochemical parameters were measured using spectrophotometric methods [TBARS, TEAC and catalase (CAT) and GST activities] and a chromatographic method [glutathione (GSH)]. The fetal Hb (Hb F) levels observed in the SCA (+HU) group (10.9%) confirmed the already well-described pharmacological effect of HU, but the SCA (-HU) group also had high Hb F levels (6.1%), which may have been influenced by genetic factors not targeted in this study. We found a higher frequency of the Bantu haplotype (48.2%), followed by the Benin (32.1%) and also Cameroon haplotypes, rare in our population, and 19.7% of atypical haplotypes. The presence of Bantu haplotype was related to higher lipid peroxidation levels in patients, but also, it conferred a differential response to HU treatment, raising Hb F levels in 52.6% (P = 0.03). The protective effect of Hb F was confirmed, because the increase in their levels resulted in a 41.3% decrease in lipid peroxidation levels (r = -0.74, P = 0.0156). The genotypic frequency of the GST polymorphisms observed was similar to that of other studies in the Brazilian population, and its association with biochemical markers revealed a significant difference only for the GSTP1 polymorphism, where patients with genotype V/V showed higher GSH and TEAC levels (P = 0.04 and P = 0.03, respectively) compared to patients with genotype I/I. The TBARS levels were about five to eight times higher in the SCA (+HU) and SCA (-HU) groups, respectively, compared to controls, and HU produced a 35.2% decrease in lipid peroxidation levels in the SCA (+HU) group (P < 0.0001). Moreover, the SCA (+HU) group showed higher TEAC levels when compared to CG (P = 0.002). We did not find any significant difference in GST activity between the groups studied (P = 0.76), but CAT activity was about 17 and 30% lower in SCA (+HU) and SCA (-HU) groups, respectively (P < 0.00001). Plasma GSH levels were ~2 times higher in SCA patients than in the control group (P = 0.0005) and showed a positive correlation with TBARS levels, confirming its antioxidant function. HU treatment contributed to higher CAT activity and TEAC levels and lower lipid peroxidation, and its pharmacological effect showed a “haplotype-dependent” response. These findings may contribute to elucidating the potential of HU in ameliorating oxidative stress in SCA subjects.

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Eukaryotic translation initiation factor 5A (eIF5A) is the only cellular protein that contains the polyamine-modified lysine, hypusine [Nε-(4-amino-2-hydroxybutyl)lysine]. Hypusine occurs only in eukaryotes and certain archaea, but not in eubacteria. It is formed post-translationally by two consecutive enzymatic reactions catalyzed by deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). Hypusine modification is essential for the activity of eIF5A and for eukaryotic cell proliferation. eIF5A binds to the ribosome and stimulates translation in a hypusine-dependent manner, but its mode of action in translation is not well understood. Since quantities of highly pure hypusine-modified eIF5A is desired for structural studies as well as for determination of its binding sites on the ribosome, we have used a polycistronic vector, pST39, to express eIF5A alone, or to co-express human eIF5A-1 with DHS or with both DHS and DOHH in Escherichia coli cells, to engineer recombinant proteins, unmodified eIF5A, deoxyhypusine- or hypusine-modified eIF5A. We have accomplished production of three different forms of recombinant eIF5A in high quantity and purity. The recombinant hypusine-modified eIF5A was as active in methionyl-puromycin synthesis as the native, eIF5A (hypusine form) purified from mammalian tissue. The recombinant eIF5A proteins will be useful tools in future structure/function and the mechanism studies in translation.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)